Wal-Mart has rollback sales throughout the year, and they usually last about three months. And while rollback prices are lower, they're not usually as low as Wal-Mart's Black Friday deals. But neither company has specified prices nor announced which items will be on sale.

Along with the rollback prices, Wal-Mart is dropping its free shipping minimum order to $35 from $50. Coincidentally, $35 just so happens to be the minimum order price to get Amazon's free shipping.

Wal-Mart.com CEO and President Fernando Madeira wrote on Wal-Mart's blog, "We're standing up for our customers and everyone else who sees no rhyme or reason for paying a premium to save."

Now despite the CEO's corporate fightin' words, signing up for Amazon's Prime service comes with more than just entry to this one-day sale; it gives users access to movies, TV shows, free shipping and other perks.

But Wal-Mart is fighting an uphill battle with Amazon for e-commerce business. In 2014, Wal-Mart increased its e-commerce sales 22 percent, bringing its online revenue to $12 billion. During that same year, Amazon brought in almost $89 billion in net sales.